This is a competing renewal of a training program designed to prepare highly qualified individuals with prior training in developmental medicine for an investigative career by providing them the necessary skills to conduct collaborative research related to the Development of Cardiovascular and Pulmonary Function. Since its inception 29 years ago, the program has provided an in-depth research experience intended to teach the fundamentals of scientific investigation by the direct association of trainees with established investigators in a number of areas of biomedical science. Trainees spend 2-3 years participating in all activities of a research experience, and under the direct supervision of a training faculty member, take primary responsibility for a project. Training faculty are members of many clinical and basic science departments in the Yale School of Medicine, including Pediatrics, Pathology, Genetics, Cellular and Molecular Physiology, Internal Medicine and Immunobiology. In addition to a focused and intense research experience, the program has a core curriculum designed to provide basic skills in experimental design/analysis (for both basic and clinical research), data presentation, biostatistics, grant preparation and ethical scientific conduct. Most trainees are selected from a large, highly competitive pool of physicians from Yale and other institutions who are trained in pediatrics and desire a strong foundation in biomedical research in order to become independent investigators. While the program has emphasized research training for exemplary physicians, Ph.Ds seeking postdoctoral training in cardiopulmonary research are strongly encouraged to apply and have been supported in recent funding periods. Because most of the physician trainees need clinical as well as research training, the three clinical sections that primarily support this training grant have secured separate (non-NIH) funding to support the necessary advanced clinical training. Thus, the effort supported by this training grant is devoted to the acquisition of research skills. Additionally, the program director and training faculty view this grant as a vehicle to initiate career development in collaborative biomedical investigation and not as a mechanism to fully complete an trainee's research training. Thus trainees are encouraged to apply for extramural support to extend their research training, and they have been quite successful in obtaining such support.